The present invention relates to a hub unit to be used in the wheels of an automobile, etc.
A conventional hub unit of this type is provided with an outer ring member, an inner ring member which has a large diameter part and a small diameter part, said small diameter part having a threaded end, a sleeve which fits over the small diameter part of the inner ring, and rolling elements which are positioned between the large diameter part of the inner ring member and the inner surface of the outer ring member and between the outer surface of the sleeve and the inner surface of the outer ring member. The sleeve is tightened by screwing a nut on the threaded end toward a step between the large and small diameter parts of the inner ring member and caulking such a fitting.
However, because the sleeve is tightened and fixed to the inner ring member by a nut, the conventional hub unit is not able to secure the sleeve without turning the nut a certain number of revolutions, thus being disadvantageous in that the time required for assembling the hub unit is long. Furthermore, with the conventional hub unit, there is the additional problem that the tightening torque of the nut must be strictly controlled. Moreover, because threads must be provided on the inner ring member, there is the additional problem that the size of the overall hub unit is relatively large in the axial direction.